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Norwegian VAT return (MVA-melding) filing for Java — ID-porten, Altinn, Skatteetaten

1 starsJava

mva-melding-java – Java library for Norwegian VAT filing via Altinn 3

by guanghu·Apr 6, 2026·2 points·0 comments
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AI Analysis

●●SolidNiche GemSolve My Problem

Handles reverse-charge codes 81/83/86/88/91 double-entry rules correctly.

Strengths
  • •Built from 3 years of production accounting platform code, not theoretical
  • •Ports-and-adapters architecture lets you plug in any ledger backend
  • •Handles Norwegian public-holiday-adjusted filing deadlines automatically
Weaknesses
  • •Extremely narrow audience (only Norwegian VAT filers using Java)
  • •No Spring Boot starter included for the main VAT library itself
Target Audience

Norwegian fintech developers, accounting SaaS builders

Similar To

Altinn SDK · Digdir ID-porten clients

Post Description

Built this after 3 years developing a SaaS accounting system for the Norwegian market.

The hard part of MVA-melding isn't the XML — it's the full auth and submission chain: ID-porten PKCE with private_key_jwt, then Altinn 3's multi-step instance lifecycle (create → upload → sign → complete → poll feedback), plus Skatteetaten's non-obvious sign rules for reverse-charge codes (81/83/86/88/91 generate double entries).

The library handles the complete 15-step flow and uses a ports-and-adapters design — you implement one interface to connect your own ledger data.

Also open-sourced a companion Spring Boot starter for EHF 3.0 / PEPPOL BIS Billing 3.0 invoice transmission.

https://github.com/guangcode/mva-melding-java https://github.com/guangcode/oxalis-spring-boot-starter

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